Active users is GA4’s count of distinct users who engaged with your website or app during a period, where a user is really a browser or device rather than a person. When a standard GA4 report says “Users”, it is showing active users.
How active users works
GA4 records events, and each event carries an identifier for the browser or app it came from. A user counts as active in a period if GA4 recorded any of the following for them:
- an engaged session, which by default means a session lasting longer than 10 seconds, a session with a key event, or one with at least two page or screen views;
- a first visit to a website, or a first open of an app;
- any engagement time, which GA4 measures while the page or app is in the foreground.
GA4 also has a separate metric called total users, which counts every distinct user who triggered any event at all. The two figures are usually close, but active users can be lower on sites where many visits close almost instantly. Universal Analytics, which Google retired in 2023 and 2024, used total users as its headline “Users” figure, which is one reason GA4 numbers never matched old reports exactly.
Who counts as one user depends on your reporting identity setting. The default combines a user ID, if your site sends one for logged-in customers, with the device’s cookie identifier and, where the property qualifies, modelled data. Without a user ID, the same person on a work laptop and a personal phone is two users, and someone who clears their cookies, or returns after Safari has expired GA4’s cookie, appears as a new one.
Why it matters
Active users is the denominator in many numbers businesses report, from user conversion rate to revenue per user, so its quirks flow into everything built on it.
In the UK it is also shaped by consent. Analytics cookies generally need a visitor’s agreement under PECR, so a site with a proper cookie banner does not observe people who decline. Consent mode can estimate some of that activity, but estimates are not observations. The user count usually falls when a business adds a compliant banner. That fall is a change in measurement, not in demand, and it needs marking in your reports so nobody mistakes it for a collapse in interest.
Because the count is device-based, it is best read as a trend rather than a headcount. It tells you whether your reach is growing, shrinking or flat. It does not tell you how many people in Croydon or Leeds know your business exists.
Common mistakes
- Comparing GA4 active users with Universal Analytics users and concluding traffic fell, when the two metrics were defined differently.
- Adding up daily active users to get a monthly figure. Someone who visits on five days is one monthly user but five daily ones.
- Comparing user numbers across the date a cookie banner went live without noting the change.
- Reading active users as potential customers. Many are existing customers, job seekers, suppliers or competitors.
- Setting up a user ID that sends an email address. Google’s terms forbid sending personally identifiable information to Analytics; use an internal reference that identifies nobody on its own.
How to act on it
Use active users for trend lines and context, and make decisions on outcomes. Check which acquisition report you are reading before drawing conclusions: GA4’s User acquisition report credits the channel that first brought each user, while the Traffic acquisition report credits the channel behind each session.
Add an annotation for anything that changes how users are counted: a cookie banner, a domain change, a site rebuild, a new reporting identity. If customers log in, consider sending a non-identifying user ID so returning customers on several devices are counted once.
When the real question is how many potential customers you reach and what it costs to turn them into enquiries, user counts are the start of the analysis rather than the answer. Building reports that connect reach to leads and revenue is part of the digital marketing strategy work I do with UK businesses.